These look rather like a hazard, but I suspect
someone would prefer making them a full monster.
Who is this person?
Anyway, we've got precedence for creature here. See the giant leech in Stormwrack.
We can downsize it to Tiny, giving us...
Small Vermin (Aquatic)
Hit Dice: 1/4d8 (1 hp)
Initiative: +2
Speed: Swim 10 ft. (2 squares)
Armor Class: 14 (+2 size, +2 Dex), touch 14, flat-footed 12
Base Attack/Grapple: +0/-12
Attack: Touch +4 melee (attach)
Full Attack: Touch +4 melee (attach)
Space/Reach: 2-1/2 ft./0 ft.
Special Attacks: Attach, drain psionics, psychic blast
Special Qualities: Blindsight 10 ft., detect psionics, scent
Saves: Fort +2, Ref +2, Will -1
Abilities: Str 2, Dex 14, Con 11, Int -, Wis 8, Cha 2
Skills: Hide +18, Swim +4
Feats: Weapon Finesse (B)
Environment: Warm marsh
Organization: Colony (2-5) or swarm (6-11)
Challenge Rating: x
Treasure: None
Alignment: Always neutral
Advancement: x
Level Adjustment: -
Attach (Ex): If a psionic leech hits with its touch attack, it uses the tiny hooks along its body to latch onto the opponent’s body. It deals no additional damage when it is attached. An attached leech loses its Dexterity bonus to AC and has an AC of 12.
An attached psionic leech can be struck with a weapon or grappled itself. To remove an attached leech through grappling, the opponent must achieve a pin against the creature.
Skills: Psionic leeches have a +4 racial bonus on Hide checks. A giant leech has a +8 racial bonus on any Swim check to perform some special action or avoid a hazard. It can always choose to take 10 on a Swim check, even if distracted or endangered. It can use the run action while swimming, provided it swims in a straight line.